全文获取类型
收费全文 | 802篇 |
免费 | 63篇 |
国内免费 | 22篇 |
出版年
2023年 | 12篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 21篇 |
2019年 | 21篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 24篇 |
2015年 | 22篇 |
2014年 | 28篇 |
2013年 | 45篇 |
2012年 | 18篇 |
2011年 | 35篇 |
2010年 | 17篇 |
2009年 | 43篇 |
2008年 | 30篇 |
2007年 | 47篇 |
2006年 | 36篇 |
2005年 | 38篇 |
2004年 | 44篇 |
2003年 | 33篇 |
2002年 | 28篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 30篇 |
1998年 | 9篇 |
1997年 | 17篇 |
1996年 | 15篇 |
1995年 | 8篇 |
1994年 | 16篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有887条查询结果,搜索用时 15 毫秒
51.
52.
53.
Xu W Royalty MP Zimmerman JR Angus SP Pennock DG 《The Journal of eukaryotic microbiology》1999,46(6):606-611
The dynein ATPases are a family of motor enzymes that drive microtubule sliding in cilia and flagella and contribute to microtubule-based transport inside cells. The multi-dynein hypothesis makes two predictions: 1) Axonemes contain multiple dynein heavy chain (DHC) isoforms, each encoded by a different gene; 2) Each isoform performs a specific role in ciliary beating. We used PCR-based techniques to clone thirteen different DHC sequences from Tetrahymena genomic DNA. All thirteen genes appeared to be expressed in growing cells. Comparisons of the deduced amino acid sequences of the thirteen DHCs with other known DHCs suggested that we have cloned three outer arm DHCs, two cytoplasmic DHCs, and eight inner arm DHCs. 相似文献
54.
Boileau AJ Kissmehl R Kanabrocki JA Saimi Y 《The Journal of eukaryotic microbiology》1999,46(1):56-65
Methods for mass transformation of Paramecium tetraurelia were established using plasmids bearing neomycin-resistance or calmodulin gene fragments. Phenotypic and molecular analyses showed that, although variable, up to 5% transformation can be achieved by electroporation. Concentrations of divalent cations Ca2+ and Mg2+ in the electroporation medium were crucial for efficient transformation. Strong neomycin-resistance transformation using bioballistic particle bombardment with gold particles was observed. For both methods, hybridization to transformant DNA revealed plasmid signals consistent with macronuclear transformation and correlated with transformed phenotypes. Complementation of a known calmodulin gene mutation was also achieved by mass transformation. Possible sources of variation and the general utility of these methods are discussed. 相似文献
55.
Infraciliature and myoneme system of Campanella umbellaria (Protozoa, Ciliophora, Peritrichida) 总被引:1,自引:0,他引:1
The infraciliature and myoneme system of Campanella umbellaria were revealed using the protargol impregnation technique. The main characteristics of the infraciliature are the peristomial ciliary rows (haplokinety and polykineties), which make four and a half turns around the peristomial disc before plunging into the infundibulum, and the aboral infraciliature, which is made up of the aboral ciliary wreath (trochal band) and the scopula. The myoneme system is composed of: 1) longitudinal fibers, which include 60-84 (mean 72.3) short longitudinal fibers, 40-56 (mean 45.8) medium-length longitudinal fibers, and numerous long longitudinal fibers; and 2) circular fibers, which include 8-12 (mean 9.3) peristomial ring fibers, linking fibers, support fibers, and peristomial disc fibers. The various fibers in C. umbellaria are interconnected to form a single myoneme system that may act as a cell skeleton as well as providing the mechanism by which the zooid contracts and relaxes. 相似文献
56.
Lavelle P Blouin M Boyer J Cadet P Laffray D Pham-Thi AT Reversat G Settle W Zuily Y 《Comptes rendus biologies》2004,327(7):629-638
The use of pesticides to control plant parasites and diseases has generated serious problems of public health and environmental quality, leading to the promotion of alternative Integrated Pest Management strategies that tend to rely more on natural processes and the active participation of farmers as observers and experimenters in their own fields. We present three case studies that point at different options provided by locally available populations of soil organisms, the maintenance of diverse populations of pests or increased resistance of plants to pest attacks by their interactions with earthworms and other useful soil organisms. These examples demonstrate the diversity of options offered by the non-planned agro-ecosystem diversity in pest control and the need to identify management options that maintain this biodiversity. 相似文献
57.
During a survey of the ciliate protozoal composition of the stomach contents of nine dromedary camels of Egypt, fourteen morphotypes of Entodinium ovumrajae, which has been considered as a species peculiar to camels, were found in six camels. Except for five morphotypes including one originally described as an independent species and its forms, these were newly detected. These morphotypes, divided into three groups, can be identified mainly by the morphology of their ectoplasmic processes. Each camel had on average, about five morphotypes of this species. 相似文献
58.
Two euplanktonic ciliates, Urotricha psenneri n. sp. (Prostomatida) and Amphileptus piger (Vuxanovici, 1962) n. comb. (Pleurostomatida), were discovered in the surface plankton of the oligotrophic Lake Traunsee in Austria. Their morphology and infraciliature were studied in live cells as well as in specimens impregnated with protargol and silver nitrate. Urotricha psenneri is a small urotrichid, less than 50 microm length and with a single caudal cilium. It is unique in having (i) a massive oral basket projecting as a conspicuous bulge with cylindrical microfibrillar annulus and (ii) a curved brosse row 1 in the broad, barren circumoral area. Amphileptus piger (Vuxanovici, 1962) is about 55 x 13 microm in vivo, has two macronuclear nodules with a single micronucleus in between in the posterior body half, has a single contractile vacuole with a terminal excretory pore, and few, but thick and thus highly conspicuous extrusomes. The amphileptid ciliary pattern (spica) is difficult to recognise due to the widely spaced basal bodies. 相似文献
59.
The ciliate Sorogena stoianovitchae, which can form a multicellular fruiting body, has been classified based upon its ultrastructure and morphology: the oral and somatic infraciliature of S. stoianovitchae most closely resemble those of members of the order Cyrtolophosidida in the class Colpodea. We characterized the small subunit ribosomal DNA (SSU rDNA) gene sequence from S. stoianovitchae and compared this sequence with those from representatives of all ciliate classes. These analyses placed S. stoianovitchae as either sister to members of the class Nassophorea or Colpodea. In an in-group analysis, including all SSU rDNA sequences from members of the classes Nassophorea and Colpodea and representatives of appropriate outgroups, S. stoianovitchae was always sister to Platyophrya vorax (class Colpodea, order Cyrtolophosidida). However, our analyses failed to support the monophyly of the class Colpodea. Instead, our data suggest that there are essentially three unresolved clades: (1) the class Nassophorea; (2) Bresslaua vorax, Colpoda inflata, Pseudoplatyophrya nana, and Bursaria truncatella (class Colpodea); and (3) P. vorax and S. stoianovitchae (class Colpodea). 相似文献
60.
Phytoseiid predators suppress populations of Bemisia tabaci on cucumber plants with alternative food
Phytoseiids are known to attack whiteflies, but it is an open question whether they can be used for biological control of
these pest insects. Preselection experiments in the laboratory showed that two out of five phytoseiid species tested, Euseius scutalis and Typhlodromips swirskii, stood out in terms of their ability to develop and reproduce on a diet of Bemisia tabaci immatures. In this paper, we show that both predators are able to suppress whitefly populations on isolated cucumber plants
in a greenhouse. Predatory mites were released 2 weeks in advance of the release of B. tabaci. To enable their survival and promote their population growth, they were provided weekly with alternative food, that is,
Typha sp. pollen. A few weeks after whitefly introduction, the numbers of adult whiteflies on plants with predators were consistently
lower than on plants without predators, where B. tabaci populations grew exponentially. After 9 weeks, this amounted to a 16- to 21-fold difference in adult whitefly population
size. This shows that the two phytoseiid species are promising biocontrol agents of B. tabaci on greenhouse cucumber.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献